1. Field of the Invention
The present invention relates to a toner for developing an electrostatic latent image and a manufacturing method thereof. Specifically, the present invention relates to a toner for developing an electrostatic latent image and a manufacturing method thereof in which filming can be suppressed and low temperature fixing performance can be maintained while also being able to maintain fluidity.
2. Description of Related Art
Lately, in order to realize reduction of power consumption, increase of print speed, and widening the variety of types of paper that can be applied, a technique referred to as low temperature fixing which is a technique to fix toner images on a medium such as paper at a temperature lower than conventional techniques is gathering attention. Regarding toner, toner with a core shell structure made by providing a shell layer on the surface of a core particle is developed and by including styrene-acrylic type resin in the core particle and styrene-acrylic modified polyester resin in the shell layer, a toner (hereinafter referred to as “toner”) for developing an electrostatic latent image with preferable low temperature fixing performance and fixing/separating performance can be obtained (for example, see Japanese Patent Application Laid-Open Publication No. 2013-33233).
With the fixing at low temperature and reduction of particle size of toner advancing, since the stirring strength in the developing device increased due to the increase of print speed, the mechanical stress that the developer receives by stirring has increased. Due to such mechanical stress, a phenomenon called “filming” occurs where a fragment of the toner particle or a component of the toner mother particle attaches to a photoreceptor or a surface of the carrier. When filming occurs and a large number of sheets are printed, defects in images could occur or applying the suitable charging amount to the toner could become difficult.
Therefore, the following toner is proposed where a convex portion is formed on a surface of the toner mother particle to make the contact area with other members small, hard fixing resistance with other members is maintained while maintaining low temperature fixing performance, and an image with high quality is formed (for example, see Japanese Patent Application Laid-Open Publication No. 2011-95286).
Also the following toner is reported where in order to prevent crushing of the convex portion due to mechanical stress, cross linked resin with a cross linked structure is used as the resin particle composing the convex portion (for example, see Japanese Patent Application Laid-Open Publication No. 2012-163694).
However, according to the technique described in Japanese Patent Application Laid-Open Publication No. 2011-95286 and Japanese Patent Application Laid-Open Publication No. 2012-163694, the hardness of the resin and the Young's modulus composing the convex portion is not considered. Therefore, there is a problem that the convex portion is buried in the toner mother particle due to mechanical stress and the filming is not suppressed sufficiently. Moreover, since styrene type resin is included as the resin composing the convex portion, there is a problem that the low temperature fixing performance is not enough.
Moreover, according to the technique of Japanese Patent Application Laid-Open Publication No. 2011-95286, there is a problem that the covering percentage of the convex portion is high, and the fluidity of the toner particle is not enough.